Describe the relationship among the various hemoglobin's in first year of life and their implication in diagnosing hereditary hemoglobinopathies.

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Hemoglobin is tetramer of 4 globin chain + heme( Fe containing porphyrin ring).

Hb F has 2 alpha chains and 2 beta chains which is replaced by Hb A which has 2 aplha chains and 2 beta chains.

Hemoglobin F   -   α2 γ2

Hemoglobin A   -  α2 β2

Normal replacement goes as below

• By 6-8wk HbF is predominate hb
• By 24wk 
• HbF constitute 90% of Hb
• HbA constitute 5-10% of Hb
• By 6-12mo postnatal age
• HbF is <2% of total Hb
• HbA reaches adult level

There could be deviations in this replacement due to mutations in gene which cause replacement of amino acids and forms defective hemoglobins.

Diagnosis is done by HPLC (High Performance Liquid Chromatography) or IEF (Thin layer/Isoelectric Focusing). 

F - fetal Hb

S - sickle Hb

SS - Homozygous SCD

AS - Sickle cell trait

Sβ - Sickle thalassemia

C -  Hb C

SC - sickle-hemoglobin C

A stands for adult Hb

HPFH - Hereditary Presence of Fetal Hemoglobin

Hb are written from greater to lower quantity.

Report	Possibilities
FS	SCD SS SCD Sβ thal S HPFH
FSC	SCD SC
FSA	SCD Sβ thal (Hb S>50%, HbA2>3.5%)
FAS	SCD AS (rule out blood transfusion)
AFS	Transfusion is received so can be SCD SS SCD Sβ thal
FS Other	SCD Sβ thal SCD SD, SO, SC, S

F98%A22%	β thalassemia major
A65-88%F10-30%,A22-5%	β thalassemia intermediate
↑ A2, variable F	β thalassemia trait
A2 absent	𝛿 thalassemia
Bart: 1-2%	α thalassemia 1 gene deletion
Bart: 5-10%	α thalassemia 2 genes deletion
Bart: 20-30%	α thalassemia 3 genes deletion
Bart: 90% c Grower 1,2 & Portland	α thalassemia 4 genes deletion